[intfsorch] Create subport with the entry contains necessary attributes

[peter-yu]

redis APPL_DB has two entries for subport
8) "INTF_TABLE:Ethernet4.20"
9) "INTF_TABLE:Ethernet4.20:192.169.1.1/24"

sometimes, if the entry with ip key are execute first,
the syslog is like
Feb 23 02:20:43.650184 as7726-32x-3 NOTICE swss#orchagent: :- addRouterIntfs: Create router interface Ethernet4.20 MTU 32761
Feb 23 02:20:43.651383 as7726-32x-3 ERR syncd#syncd:[none] brcm_sai_create_router_interface:284 Invalid MTU size

the mtu value is not init and is too large. sai will return SAI_STATUS_INVALID_PARAMETER

Thus, mtu should be initialized to 0

What I did
initialize mtu to 0
Why I did it
sometimes gPortsOrch->addSubPort(port, alias, adminUp, mtu) is called and
the mtu value is not init and is too large. sai will return SAI_STATUS_INVALID_PARAMETER

Thus, mtu should be initialized to 0

How I verified it
create/remove subport interface many times

Details if related

[ghost]

I'd extend PR description to explicitly mentioned that in case MTU=0 the subport will inherit MTU value from the parent port.

[wendani]

Port object is not supposed to be created by "INTF_TABLE:Ethernet4.20:192.169.1.1/24".

In current fix, sub interface admin_status still faces a similar issue that adminUp get some random init value, most likely non-zero, to cause interface SAI ADMIN_STATE to be "true", ignorant of user config in CONFIG_DB.

Try

"INTF_TABLE:Ethernet4.20": {
    "admin_status": "false"
}

You will still get ADMIN_V4_STATE and ADMIN_V6_STATE to be "true" in ASIC_DB output.

1) "SAI_ROUTER_INTERFACE_ATTR_VIRTUAL_ROUTER_ID"
 2) "oid:0x3000000000022"
 3) "SAI_ROUTER_INTERFACE_ATTR_SRC_MAC_ADDRESS"
 4) "02:42:AC:11:00:04"
 5) "SAI_ROUTER_INTERFACE_ATTR_TYPE"
 6) "SAI_ROUTER_INTERFACE_TYPE_SUB_PORT"
 7) "SAI_ROUTER_INTERFACE_ATTR_PORT_ID"
 8) "oid:0x1000000000012"
 9) "SAI_ROUTER_INTERFACE_ATTR_OUTER_VLAN_ID"
10) "10"
11) "SAI_ROUTER_INTERFACE_ATTR_ADMIN_V4_STATE"
12) "true"
13) "SAI_ROUTER_INTERFACE_ATTR_ADMIN_V6_STATE"
14) "true"
15) "SAI_ROUTER_INTERFACE_ATTR_MTU"
16) "32761"
17) "SAI_ROUTER_INTERFACE_ATTR_NAT_ZONE_ID"
18) "0"

I believe on line 745, we need to amend the condition to create Port object with && !ip_prefix_in_key as root fix, though it does no harm to give mtu an explicit init value. To be consistent, we should do the same treatment to adminUp as mtu. I have reproduced this issue using vs docker, and have crafted a vs test case to validate the root fix.

AssertionError: Expected field/value pairs not found: expected={'SAI_ROUTER_INTERFACE_ATTR_TYPE': 'SAI_ROUTER_INTERFACE_TYPE_SUB_PORT', 'SAI_ROUTER_INTERFACE_ATTR_OUTER_VLAN_ID': '10', 'SAI_ROUTER_INTERFACE_ATTR_ADMIN_V4_STATE': 'false', 'SAI_ROUTER_INTERFACE_ATTR_ADMIN_V6_STATE': 'false', 'SAI_ROUTER_INTERFACE_ATTR_MTU': '9100', 'SAI_ROUTER_INTERFACE_ATTR_VIRTUAL_ROUTER_ID': 'oid:0x3000000000022'}, received={'SAI_ROUTER_INTERFACE_ATTR_VIRTUAL_ROUTER_ID': 'oid:0x3000000000022', 'SAI_ROUTER_INTERFACE_ATTR_SRC_MAC_ADDRESS': '02:42:AC:11:00:02', 'SAI_ROUTER_INTERFACE_ATTR_TYPE': 'SAI_ROUTER_INTERFACE_TYPE_SUB_PORT', 'SAI_ROUTER_INTERFACE_ATTR_PORT_ID': 'oid:0x1000000000012', 'SAI_ROUTER_INTERFACE_ATTR_OUTER_VLAN_ID': '10', 'SAI_ROUTER_INTERFACE_ATTR_ADMIN_V4_STATE': 'true', 'SAI_ROUTER_INTERFACE_ATTR_ADMIN_V6_STATE': 'true', 'SAI_ROUTER_INTERFACE_ATTR_MTU': '32630', 'SAI_ROUTER_INTERFACE_ATTR_NAT_ZONE_ID': '0'}, key="oid:0x60000000005f6", table="ASIC_STATE:SAI_OBJECT_TYPE_ROUTER_INTERFACE"

[peter-yu]

Thanks. Done.

[wendani]

as comments

[wendani]

Should be with line 745

[peter-yu]

Done.